Almost 40% of new therapeutic agents and over 30% of pipeline pharmaceuticals exhibit poor water solubility which provides challenges in delivery, such as the delivery of therapeutic levels of pharmaceuticals to achieve a desired therapeutic outcome. Furthermore, many drugs have side effect profiles that make it advantageous to be able to deliver directly to the site of action thereby minimizing the amount of drug required for a given therapeutic effect.
While liposomes, nanoemulsions and dendrimers have been used to package pharmaceuticals for delivery, they often require complex preparation procedures, use solvents not suitable for pharmaceutical use and/or result in polydisperse structures that are difficult to define and characterize to a level that allows pharmaceutical registration. Complex polymer architectures, such as dendrimers, also lack a safe history of in vivo use. Addition of pharmacokinetic modifying agents and/or targeting agents to liposomes, nanoemulsions and dendrimers adds complexity and polydispersity to these structures.
There is a need for pharmaceutical delivery carriers that are easy to prepare in the absence of non-pharmaceutical solvents, can carry a variety of pharmaceuticals, have appropriate pharmacokinetic properties including stability under biological conditions and/or deliver a pharmaceutical to a particular tissue or receptor. Additionally these pharmaceutical delivery vehicles should encapsulate or shield the pharmaceutical and deliver it in a concentrated fashion to the site of desired action, meanwhile masking it from immune clearance. There is a further need for pharmaceutical delivery carriers to deliver low amounts of pharmaceutical (e.g. antigenic protein) to specific cell types (e.g. dendritic cells) in a targeted fashion, in order to induce a sub-immunogenic activation of T cells. Alternatively, a concentrated bolus of pharmaceutical, for example a chemotherapeutic agent, should be delivered to cells again in a targeted fashion, so as to kill the target cell(s).